Abstract
Aims: To measure the microhardness of root canal dentin using two types of irrigating solutions( 0.2% Chlorhexidine and 5.25% Sodium Hypochlorite) with and with out use of different types of root canal files (Stainless Steel-K files, Nickel-Titanium K-files or rotary Nickel-Titanium files). Materials & methods: The teeth divided in to four groups according to the type of irrigating solutions that used during root canal instrumentation with the use of normal saline as a control group, then each group sub divided in groups according to the instrument used in the root canal preparation, then after irrigation and preparation the roots sliced and root dentin microhardness measured using Vicker,s microhardness machine. Results: The result of this study showed that the type of instrument and Chlorhexidine have no effect on the microhardness of root canal dentin while Sodium Hypochlorite significantly decrease the microhardness of root canal dentin especially when use with Stainless Steel K-files and Nickel-Titanium K-files than when used with rotary Nickel-Titanium files. Conclusion: The microhardness of root canal dentin not affected by the type of root canal instruments.,The use of 5.25% Sodium Hypoch-lorite as a root canal irrigation significantly reduce the microhardness of root dentin within 3 mi-nutes., The use of Sodium Hypochlorite as a root canal irrigant with stainless steel K-files or Nickel-Titanium K-files reduce the microhardness of root canal dentin to greater extend than when use with rotary Nickel-Titanium files because the working time required with Stainless Steel K-files or Nickel-Titanium K-files was on the average three times longer than the working time with rotary Nickel-Titanium files. The use of sodium hypochlorite as a root canal irrigant with stainless steel K-files or Nickel-Titanium K-files reduce the microhardness of root canal dentin
Highlights
Dentin microstructure and its properties are very important in restorative dentistry
The method used in this study was described by Dayal et al and Slutzky Goldgerg et al,(4,13) in this method the teeth was collected and cleaned the access to the root canal was prepared and the pulp tissue extirpated after that the teeth divided in groups according to the type of the instrument that used in the root canal preparation, after root canal preparation each root sectioned transversely and the hardness of root canal dentin measured. ( 4,13), In this study after access cavity preparation and pulp extirpation, the teeth divided in to the following groups: Group A: Ten teeth were kept as control, neither instrumented nor irrigated
The result of this study demonstrated that the instrumentation with stainless steel K-files, Nickel-Titanium K-files and rotary Nickel-Titanium files have no significant effects on the root dentin microhardness when use with normal saline. this mean that the types of the instrument not produce any changes in the organic and inorganic component of root canal dentin
Summary
Dentin microstructure and its properties are very important in restorative dentistry. Dentin is a hydrated complex composed of four elements: [1] oriented tubules surrounded by [2] a highly mineralized peritubular zone embedded in an intertubular matrix consisting largely of [3] type I collagen with apatite crystals and[4] dentinal fliud.[1] Knowledge of mechanical properties of human root canal dentin would help restorative treatment. Hardness measurement can be correlated with the other mechanical properties such as fracture resistance, www.rafidaindentj.net. Al-Ashou WMO modulus of elasticity and yield strength. A strong relationship exists between microhardness of dentine and restorative bond strength. Microhardness provides a first step toward predicting behavior of dentin/ restoration interfaces.[2]
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